The present invention relates to a locking device, a new and improved hasp, and more specifically to a locking device which includes a new combination of components, namely, the hasp and a round cylinder lock protectively embedded in an indentation built into the hasp. The hasp is designed to be used with a round cylinder lock of the type disclosed in U.S. Pat. No. 3,769,821 and sold by the American Lock Company. This invention is able to provide a highly versatile locking system for use in a number of different structures such as sliding doors on the backs of trucks, on store fronts, on garage doors, on warehouses, and the like. This locking device makes it more difficult for burglars to penetrate since there is no easy way to cut the lock open or to pry the lock from the uniquely constructed hasp. In my invention, I have provided a hasp for a round cylinder lock. The hasp is comprised of a steel reinforced plate. The steel reinforced plate has a truncated circular indentation on a front side thereof for encapsulating an outer diameter of the round cylinder lock. The truncated circular indentation also has a hasp hole. A locking pin extends from the round cylinder lock and the pin is receivable in the hasp hole. The hasp hole is sized slightly larger than the outer circumference of the locking pin. The locking pin is fixed to the round cylinder lock and extends axially outwardly thereof. A plate lug is supported on the steel reinforced plate and projects axially outwardly of the truncated circular indentation for telescoping engagement internally of the round cylinder lock. The plate lug has a plate lug hole extending at right angles to the plate lug. A sliding tubular lock shaft is located within the round cylinder lock. The plate lug is extendible into the round cylinder lock for receipt of the sliding tubular lock shaft within the plate lug hole, thereby enabling the plate lug and the hasp to be secured in locked assembly with the cylinder lock.